Relationships Between Type and Performance of Daughters of Artificial Insemination Sires

Abstract

Progeny group means of Predicted Difference milk yield, Predicted Difference fat yield, per cent of daughters with incomplete first lactations, and Descriptive Type were studied for 417 Holstein active artificial insemination (AI) sires which were production summarized in 1969-70. Three multiple regression analyses were : (1) regression of percent incomplete first lactations on Predicted Difference milk, Predicted Difference fat, and Descriptive Type; (2) regression of Predicted Difference milk on Descriptive Type, and (3) regression of per cent of sire's daughters exceeding breed-age average on Descriptive Type.Progeny average type was nearly independent of progeny average milk yield. Udder traits, with the exception of teats, appeared to be most related to utility of a sire's daughters as measured by yield and staying-ability in first lactation. Rear udder was the most consistently useful type trait for predictive purposes. In all cases, increased progeny average rear udder type was associated with increased merit for milk yield and proportion of daughters completing a first lactation. The regression of Predicted Difference milk yield on progeny average udder support and floor was significant but negative. The multiple R2 for predicting per cent incomplete first lactations, from production and type, was 15.0%. The R2 for predicting breeding value for milk from progeny type was only 8.1%.Differences among progeny means for per cent of breed-age average final type score were associated with progeny differences in stature, fore udder, rump, udder support and floor, rear udder, and front end. The R2 for predicting per cent of breed-age average type from Descriptive Type was 70.9%Descriptive Type generally had only a small association with progeny merit for production and staying-ability in first lactations.